High-speed brake.



PATENTED SEPT. 25, 1906.

w. MANN. HIGH SPEED BRAKE. APPLICATION FILED MARI), 1903. RENEWED JAN.10 1906.

wvemtoz THE NORRIS FETERS cm. WASHINQTON, A c.

UNITED STATES lfATENT OFFICE.

WILLIAM B. MANN, OF BALTIMORE, MARYLAND, ASSIGNOR TO AMERICAN AIR-BRAKECOMPANY, A CORPORATION OF NEW JERSEY.

HIGH-SPEED BRAKE.

To all whmn it natty concern:

Be it known that I, WILLIAM B. MANN, a resident of Baltimore, Maryland,have invented a new and useful Improvement in High-Speed Brakes, whichinvention is fully set forth in the following specification.

This invention relates to air-brakes for railway and other cars, andmore especially to what are known as high-speed brakes. In this class ofbrakes a very high pressure is carried in the auxiliary reservoir, whichwhen the brakes are applied, and particularly in emergency applications,equalizes the pressure between the auxiliary reservoir and thebrake-cylinder at a very high point, usually from seventy toseventy-live pounds. When the train is running at a very high speed,this pressure when exerted. through the brake-shoes upon the wheels actssimply as a braking pressure without checking the revolution of thewheels to such an extent as to cause them to slide, and thereby flattenthe wheels; but as the speed of the train decreases such a high-brakingpressure would cause the sliding and consequent fiattening of thewheels, and to obviate this it has heretofore been proposed to providemeans for lessening the pressure in the brakeeylinder, and this isusually in the form of a leak from the brake-cylinder to the atmosphere,whereby pressure begins to escape from the brake-cylinder immediatelyupon its entrance thereto. The result of this is that the pressure inthe brake-cylinder begins to decrease, and hence 'the braking pressureon the brake-shoe decreases before the speed of the train has beenmaterially checked or checked to the desired extent.

The object of the present invention is to provide a high-speed brakewhich shall utilize the high braking pressure so long as the speed ofthe train continues above apredetermined rate, and which shall thenpermit an automatic decrease of the pressure in the brake-cylinder, therate of decrease being proportionate to the decreased speed of thetrain.

l/Vith this object in View the invention consists in the usual or anysuitable auxiliary reservoir and brake-cylinder combined with arelief-valve for permitting the escape of pressure from thebrake-cylinder to the atmosphere, said valve,-however, being held closedby pressure due to the speed of the Patented Sept. 25; 1906.

Serial No- 295.482.

taining said valve on its seat is automatically decreased until thepressure from the brakecylinder acts to open the relief-valve and permitthe escape of pressure from the brakecylinder down to any predeterminedpoint, at which point the relief-valve is automatically closed by aload-spring bearing thereon.

The particular means employed to exert the pressure upon therelief-valve in order to hold it closed while the train is moving at ahigh speed is that of a load-valve, above mentioned, supplemented byair-pressure due to a compressor operated from some moving part of thecar as, for example the car-axle. This compressor is in constantoperation whether the train moves at a high or a low rate of speed;l)lll3 the amount of air compressed against the relief-valve isproportionate to the speed of the train. More specifically stated, therelief-valve is mounted upon a diaphragm open on one side to thepressure from the brake-cylinder and on the opposite side to pressure inthe cylinder communicating with the compressor, said diaphragm andrelief-valve being provided with a load-spring which normally closes therelief-valve against any pressure in the brakecylinder below thepredetermined pointsay fifty-five pounds to. the square inch. Thecylinder on the compressor side of the said diaphragm is provided with avalve opening to the atmosphere, and this valve is loaded with a springwhich retains the valve on its seat against any pressure which whenadded to the load-spring on the relief-valve would be less than thehighspeed pressure desired in the brakecylindersay seventy orseventy-five poundsand an always open leak is placed on the compressorside of the diaphragm leading to the atmosphere. As a convenient meansof construction this leak may lead directly through the vent-valvereferred to.

The inventive idea involved may receive various mechanical expressions,one of which is shown in the accompanying drawing, which is a verticalsection through the brake-cylinder and the high-speed apparatus.

Referring to the drawing, 1 is an auxiliary reservoir, 2 thebrake-cylinder, and 3 the brake-cylinder piston, of the usual or anydesired construction. Suspended to any part ofthe under side of the car,as to a beam 4, is a cylinder 5, preferably located between the axles ofone of the car-trucks, in which cylinder plays a piston 6, operated bythe connections 7 leading to an eccentric 8 on one of the axles 9 of thetruck. As here shown, the cylinder and piston constitute a single-actingcompressor, always open to the external atmosphere through the ports 10and provided with an intake-valve 11 in front of the piston. Connectedto the cylinderb is a second cylinder 12, divided transversely by adiaphragm 13, carrying a relief-valve 14, controlling a relief-port 15,leading from the cylinder to the external atmosphere. On the same sideof the diaphragm 13 as the reliefport 15 the cylinder 12 is connected tothe brake-cylinder 2 by a pipe 16, which enters the brake-cylinder infront of the brake-piston, so that the pressure in the brake-cylinderand against the diaphragm 13, tending to open the relief-valve 14, isalways equal. The relief-valve 14 is provided with a loadspring 17,reacting between the said valve and an abutment 18in the cylinder 12. Ifit is desired that the braking pressure in the brake-cylinder shallequalize at fifty-five pounds when the train is running at a moderatespeed, then the.pressure of the loadspring 17 on the diaphragm is suchas to always retain the valve closed against a pressure of fifty-fivepounds, while it will permit any pressure in excess of that to lift thevalve and reduce the pressure in the brake-cylinder until the desiredpressure of fifty-five pounds is secured. The cylinder 5 of thecompressor connects, through a port 1 9, with the cylinder 12, and thisport is controlled by a nonreturn valve 20. On the compressor side ofthe diaphragm 13 cylinder 12 is provided with a valve 21, which isloaded with a spring 22, and a leak-port 23 is also provided in saidcylinder, on the same side of the diaphragm as the valve 21, and forconvenience of construction is shown as passing directly through saidvalve.

The operation of the device is as follows: Suppose a train to be runningat a high speedsay sixty miles an hourwith a pressure of ninety poundsin the auxiliary reservoir and the proportion of the reservoir andbrake-cylinder to be such that upon an emergency application of thebrakes the pressure would equalize at seventy pounds in thebrake-cylinder, and let it also be supposed that it is desired toutilize a braking pressure of only fifty-five pounds in thebrake-cylinder when the. speed of the train is less than forty miles anhour. In this case the loadspring 17 is arranged to permit the diaphragmto yield and open the relief-valve 14 when any pressure in excess offifty-five pounds is brought against the diaphragm on the brake-cylinderside. thereof, and the spring of the valve 21 is so adjusted as to holdsaid valve 21 to its seat against any pressure in said cylinder, whichwhen combined with the power of the load-spring 17 shall be less thanthe pressure of seventy pounds on the brake-cylinder side of thediaphragm 13, but which shall open when the combined force of theload-spring 17 and the pressure in the cylinder 12 slightly exceedsseventy pounds on the brake-cylinder side of the diaphragm. Theproportion between the leak-port 23 and the compressor is such that whenthe train is running at a speed of less than forty miles an hour theleak will permit air to escape from the cylinder 12 as fast as it isforced therein by the compressor; but when the speed of the trainexceeds forty miles an hour the compressor will act to compress the airin the cylinder 12 faster than it escapes through the leak 23. As aresult of this the pressure on the compressor side ofthe diaphragm 13will rapidly increase until the pressure in the cylinder when combinedwith that of the load-spring 17 is capable of holding the relief-valve14 to its seat against a pressure of seventy pounds upon thebrakecylinder side of the diaphragm 13. Under these conditions with atrain running sixty miles an hour when an emergency application is madethe pressure in the brake-cylinder is suddenly raised to seventy pounds,and this pressure is quickly communicated to the brake-cylinder side ofthe diaphragm 13 tending to open the relief-valve 14. I This, however,is opposed by pressure on the opposite side of the diaphragm slightlyexceeding seventy pounds, and the valve is therefore held to its seatand a braking pressure of seventy pounds retained in the brake-cylinderuntil the speed of the train is reduced from sixty to forty miles anhour. As soon as or very shortly after the speed of forty miles an houris reached the pressure on the compressor side of the diaphragm 13decreases by reason of the slackened speed of the compressor and I thecontinual leak through the leak-port 23 and the pressure within. thebrake-cylinder acts upon the diaphragm 13 and opens the relief-valve,whereby the pressure in the brake-cylinder is permitted to escapethrough port 15, thereby gradually reducing the pres sure in thebrake-cylinder. This reducing action continues until the pressure in thebrake-cylinder has reached fifty-five pounds,

when the load-spring 17 acts to close the relief-valve and hold itclosed, thereby retaining the pressure of fifty-five pounds in thebrake-cylinder until the train is brought to a stop. The continuedaction of the compressor of course forces air in the cylinder 12 on thecompressor side of the diaphragm 13; but this escapes through theleak-port 23 as fast as it enters the cylinder.

It will be understood, of course, that the pressures assumed in thebrake-cylinder for high-speed and ordinary braking purposes arearbitrary in this case and are assumed merely for the purpose ofillustration and that the proportions of the compressor, leakport 23,and the load-spring 17 may be varied to suit the various conditions andpressures that may be desired in any particular case.

What is claimed is 1. In a high-speed brake, the combination of abrake-cylinder, with a relief-valve, a movable member secured thereto,devices exerting a constant force upon said member to close said valveagainst brakecylinder pressure, and an air-compressor operating inproportion to the speed of the train and compressing air to augment saiddevices.

2. In a high-speed brake, the combination of a brake-cylinder, a reliefvalve casing communicating therewith, a relief-valve controlling aventport in said casing, a diaphragm supporting said valve, a springtending to seat said valve against brake-cylinder pressure, anair-chamber to the rear of said diaphragm and an air-compressor forcingair into said chamber.

3. In a high-speed brake, the combination of a brake-cylinder, arelief-valve casing communicating therewith, a relief-valve controllinga vent-port in said casing, a diaphragm supporting said valve, a springtending to seat said valve against brake-cylinder pressure, anair-chamber to the rear of said diaphragm, an air-compressor forcing airinto said chamber, and a leak-port in the walls of said chamber.

4. In a high-speed brake, the combination of a brake-cylinder, arelief-valve casing communicating therewith, a relief-valve controllinga vent-port in said casing, a diaphragm supporting said valve, a springtending to seat said valve against brake-cylinder pressure, anair-chamber to the rear of said diaphragm, an air-compressoroperating'in proportion to the speed of the train and forcing air intosaid chamber, a leak-port in the walls of the chamber and a vent-valveopening under a predetermined pressure.

In testimony whereof I have signed this specification in the presence oftwo subscribing witnesses.

WILLIAM B. MANN.

Witnesses LEVEN J. GwINN, REEVE LEWIS.

